What is the recommended protocol for converting a patient from oxycodone to morphine?

Converting from Oxycodone to Morphine

When converting from oxycodone to morphine, use a ratio of 1:1.5 to 1:2, meaning 10 mg of oral oxycodone is equivalent to approximately 15-20 mg of oral morphine. 1, 2

Conversion Process

• Calculate the total daily oxycodone dose the patient is currently taking 1
• Convert to morphine using a ratio of 1:1.5 to 1:2 (oxycodone:morphine) 2
• Reduce the calculated morphine dose by 25-50% to account for incomplete cross-tolerance and patient variability 1
• Divide the total daily morphine dose into appropriate dosing intervals (typically every 4 hours for immediate-release formulations) 3

Example Conversion

• For a patient taking 30 mg of oxycodone twice daily (60 mg total daily dose):
  • Convert to morphine: 60 mg × 1.5 = 90 mg morphine daily 1
  • Reduce by 25-50% for cross-tolerance: 45-67.5 mg morphine daily 1
  • Divide into appropriate dosing schedule: 15-22.5 mg morphine every 4 hours as needed 3

Clinical Considerations

• Monitor patients closely for respiratory depression, especially within the first 24-72 hours following conversion 3
• Provide breakthrough pain medication during the transition period, typically 10-15% of the total daily dose 1
• Individual patient response varies greatly between different opioids, requiring close monitoring and potential dose adjustments 1
• For patients with severe pain, no washout period is needed when converting between pure opioid agonists like oxycodone and morphine 1

Potential Pitfalls and Cautions

• Avoid using fixed conversion ratios without clinical judgment, as patient variability means suggested doses are approximate 1
• Be aware that a substantial minority of patients (10-30%) may not have a successful outcome with morphine due to excessive adverse effects or inadequate analgesia 1
• If pain control remains inadequate or side effects develop, consider opioid rotation to a different agent 1
• For elderly patients (≥65 years), consider starting at the lower end of the dose range as they may be more sensitive to opioid effects 4

Dose Titration and Maintenance

• Individually titrate morphine to a dose that provides adequate analgesia while minimizing adverse reactions 3
• If the patient requires frequent breakthrough doses (more than 3 per day), consider increasing the regular scheduled dose 5
• Continually reassess pain control and monitor for development of tolerance, adverse effects, or signs of misuse 3
• For patients requiring long-term therapy, consider conversion to extended-release formulations once stable dosing is established 3